Although an earlier study clearly demonstrated that oxidized glutathione is the redox form of this metabolite that enhances in vitro transendothelial fluid transport in the rabbit cornea, results of recent studies using a thiol-blocked derivative of glutathione and an inhibitor of glutathione reductase indicate that reduction of the disulfide group is not obligatory for either the uptake or metabolism of oxidized glutathione by the corneal endothelium. Projected studies will utilize available inhibitors of Meister cycle enzymes as a means of probing the link between glutathione and the energetics of fluid transport. Treatment of lens water-insoluble proteins with borohydride, in addition to reducing disulfides, was found to produce trichloroacetic acid soluble, thiol-containing fragments in relatively greater amounts from the nuclear region of cataractous than normal lenses. This difference is being exploited to characterize changes from normal in cataractous proteins. Nuclear water-insoluble proteins will be exhaustively extracted with 7M urea to effect a fractionation of the proteins which will then be separated before and after borohydride treatment electrophoretically with and without SDS and inspected for changes in molecular weight as a means of identifying those proteins susceptible to cleavage and/or reduction. A fluorescent tag will be used for tracking thiol groups during separation procedures.